Accidental awareness under general anaesthetic, a surgical complication "greatly feared" by patients, occurs in about one in every 19,000 cases, a major new study in Ireland and the UK suggests.
What claims to be the world's largest ever study on the phenomenon, where patients report they were conscious for periods when they were supposed to be under anaesthetic, was published today by the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland.
The study found 300 spontaneous reports of accidental awareness during general anaesthesia (AAGA) out of a total of three million general anaesthetics in every public hospital in the UK and Ireland. Just 11 incidences were reported in Ireland out of all 46 acute hospitals.
The so-called NAP5 (5th National Audit Project) report said the incidence of spontaneous patient reports of awareness was “much lower” than estimates of awareness when patients were specifically asked about it after anaesthesia. In these cases, the reports were as high as 1 in 600.
Obstetric cases accounted for some 10 per cent of all reports of AAGA, making it “the most markedly over-represented of all surgical specialties”, the authors wrote. Obstetric cases account for 0.8 per cent of anaesthetics in the survey.
The incidence of reports of AAGA were also higher after cardiothoracic surgeries than for others, at one in every 8,600.
Cases of “brief awake paralysis” as a result of drug errors accounted for about 10 per cent of reports.
The majority of episodes of awareness were “short-lived, occur before surgery starts or after it finishes, and do not always cause concern to patients”, the report stated.
“Despite this, 51 per cent of episodes led to distress and 41 per cent to longer-term psychological harm.
“Sensations experienced included tugging, stitching, pain, paralysis and choking. Patients described feelings of dissociation, panic, extreme fear, suffocation and even dying. Longer-term psychological harm often included features of post-traumatic stress disorder.”
Five of the six the “certain/probable” cases of AAGA in Ireland were from adults and one was from a child aged under five. Another Irish report included one from a patient who underwent an urgent operation and later recalled having their eye examined, being paralysed and being unable to communicate.
Dr Ellen O’Sullivan, president of the College Of Anaesthetists of Ireland and project lead for the Irish study, said the phenomenon was one of the most common concerns for patients to discuss before surgery and that both patients and anesthetists ranked it high on their list of “outcomes to avoid”.
Conducted over the last three years, the study identifies risk factors and consequences for patients, including long-term psychological harm.
It also makes a number of recommendations for changes in practice to minimise the incidence of awareness and to mitigate the longer-term effects on patients.
The study says all reports of AAGA should be carefully assessed, mapping details of the patient report against the conduct of the anaesthetic care. It recommends a simple anaesthesia checklist at the start of every operation, and the introduction of a structured approach to the management of patients who report the phenomenon.
Dr O'Sullivan and Dr Wouter Jonker, consultant anaesthetist at Sligo General Hospital and co-author for the Irish study, presented the findings in Dublin today (Thursday).
“This ground-breaking project dramatically increases our understanding of anaesthetic awareness and highlights the range and complexity of patient experiences,” Dr Jonker said.